1. Technical Field
The disclosure relates generally to a method and apparatus for wirelessly receiving power.
2. Discussion of Technical Background
Wireless power transmission is the transmission of electrical energy from a power source to an electrical load without interconnecting manmade conductors. The most common form of wireless power transmission is carried out using direct induction followed by resonant magnetic induction. Other methods include electromagnetic radiation in the form of microwaves or lasers and electrical conduction. Wireless power transmission has been used for battery charging, or other suitable loads, in a wide range of mobile devices, such as mobile phone, camera, music player, headset, etc.
In a wireless power transmission system, the receiving device (receiver) may provide control information to the transmitting device (transmitter) by, for example, load modulation on the power signal. Based on the received control information, the transmitting device may adjust a certain parameter associated with the transmitted electric power, e.g., the frequency, to the desired level in order to drive the load coupled to the receiving device. Known standards, such as QI communication protocol (Wireless Power Consortium), define how the receiving device and the transmitting device communicate their power needs to each other over the same magnetic coupling used for power transmission. For example, after the initial communication between the receiving and transmitting devices is established at a default pulse-width-modulation (PWM) frequency of 175 kHz, the transmitting device transmits electric power to the receiving device with an output power up to 5 W, as supported by the current QI communication protocol. However, as some transmitting devices and receiving devices can support higher output power than 5 W, there may be a mismatch of the maximum power supported by the transmitting and receiving devices in the wireless power transmission system. Moreover, if both the transmitting and receiving devices operate with 5 W maximum, regardless of their maximum power supports, there may be a waste of resource or a loss of efficiency since both the transmitting and receiving devices may support a higher power, e.g., 10 W.
Accordingly, there exists a need for a solution for wireless power transmission to solve the above-mentioned problems.